Question

DEF is a straight angle. Find x. Then find the measures of DEC and CEF

Answer 1

x = 14, m∠DEC = 142, m∠CEF = 38

Explanation:

m∠DEF = 180

m∠DEF =m∠DEC +m∠CEF

180 = 11x-12 + 2x +10

180 =13x -2

182=13x

14 =x

m∠DEC = 11x-12 = 11x14 - 12 = 142

m∠CEF = 2x+10 = 2x14+ 10 = 38

Answer 2

x =14

DEC = 142

CEF = 38

Explanation:

Since they from a line, their sum is 180 degrees

11x-12 + 2x+10 = 180

Combine like terms

13x -2 = 180

Add 2 to each side

13x-2+2= 180+2

13x = 182

Divide each side by 13

13x/13 =182/13

x =14

DEC = 11x-12 = 11(14) -12 =154 -12 = 142

CEF = 2x+10 = 2*14+10 = 28+10 = 38